67777981 has 2 divisors, whose sum is σ = 67777982. Its totient is φ = 67777980.

The previous prime is 67777979. The next prime is 67777991. The reversal of 67777981 is 18977776.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57912100 + 9865881 = 7610^2 + 3141^2 .

It is a cyclic number.

It is not a de Polignac number, because 67777981 - 2¹ = 67777979 is a prime.

It is a super-2 number, since 2×67777981² = 9187709416872722, which contains 22 as substring.

Together with 67777979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (67777991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33888990 + 33888991.

It is an arithmetic number, because the mean of its divisors is an integer number (33888991).

Almost surely, 2^67777981 is an apocalyptic number.

It is an amenable number.

67777981 is a deficient number, since it is larger than the sum of its proper divisors (1).

67777981 is an equidigital number, since it uses as much as digits as its factorization.

67777981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1037232, while the sum is 52.

The square root of 67777981 is about 8232.7383658173. The cubic root of 67777981 is about 407.7208077282.

The spelling of 67777981 in words is "sixty-seven million, seven hundred seventy-seven thousand, nine hundred eighty-one".